A semiconductor device for a communication device uses a structure in which the surface of a sealing resin layer is covered with a shield layer in order to suppress electromagnetic disturbance such as electromagnetic interference (EMI). In order to obtain a sufficient shielding effect by the above described structure, it is preferable to electrically connect the shield layer to a ground wire, thereby releasing electromagnetic wave noise to the outside through the ground wire.
In the semiconductor device, in terms of reliability, it is preferable to improve adhesion between the shield layer and the sealing resin layer. Also, in terms of the shielding effect, it is preferable that the electric resistivity between the shield layer and the ground wire be low. In order to improve adhesion between the shield layer and the sealing resin layer, for example, a structure having a buffer layer (a base layer) formed of stainless steel (such as SUS 304) is being studied. However, the electric resistivity of stainless steel is about 72×10−8 Ωm, which is higher than, for example, the electric resistivity of a shield layer using copper or silver.